Crater counting

The method has been calibrated using the ages obtained by radiometric dating of samples returned from the Moon by the Luna and Apollo missions.

[5] Secondaries will inevitably contaminate independent crater counts leading to some who may question its effectiveness (see criticism heading for further information).

The earliest scientist to study and produce a paper using crater counting as an age indicator was Ernst Öpik, an Estonian astronomer and astrophysicist.

[7] Hartman's work includes dating the Lunar Mare to be approximately 3.6 billion years old, an age that was in accordance with isotopic samples.

[13] Planets heavily covered by water or dense atmosphere would also impede the accuracy of this method, since observational efforts would be hampered.

[14] The Earth is bombarded with approximately 100 tons of space dust, sand, and pebble particles every day; however, most of this material burns up in the atmosphere before ever reaching the surface of the planet.